Characterizing habitual and goal-directed behavioral control systems in the human brain using computational and multivariate fMRI. PI: Dr. John P. O'Doherty Institution: California Institute of Technology PROJECT SUMMARY While much is now known about the behavioral and neural mechanisms underlying goal-directed and habitual learning in rodents, much less is known about the brain structures involved in encoding the associations that support these two types of learning humans, and even less is known about the neural computations underlying their implementation. Even more critically, almost nothing is known about the mechanisms governing the transition in behavioral control between these two systems in humans. This project seeks to address these critical gaps in knowledge. To achieve this we will combine sophisticated behavioral protocols, inspired by animal studies of instrumental conditioning, with state-of-the-art fMRI data analysis. We first deploy multivariate pattern analysis techniques in order to establish the nature of associative encoding in candidate brain structures for goal-directed and habit learning such as the vmPFC, anterior and posterior striatum and supplementary motor cortex. Next, we apply sophisticated computational models to our behavioral and fMRI data in order to establish the nature of the computations underlying the implementation of these forms of learning in these brain areas. Once a clearer understanding of the neural implementation of goal-directed and habitual learning has been achieved, we turn our attention to the factors governing habitization, and to the neural systems involved in mediating the control of the habitual and goal-directed systems over behavior. For this we will apply a novel experimental paradigm developed in our laboratory that can induce behavioral habitization rapidly in human volunteers without the need for cumbersome over-training or other impractical procedures hitherto used to induce habits in humans. By combining this procedure with fMRI we will be able to directly identify brain structures engaged when behavior is under habitual control. This project will provide new insights into how habitual and goal-directed learning is implemented in the brain, and shed light on the mechanisms underlying the control of these systems over behavior. Ultimately this research has the potential to lead to the development of new mechanisms for inducing habitual control in order to achieve the maintenance of adaptive and healthful behaviors.